1. Field of the Invention
The present invention relates to a system that transports substrates for manufacturing flat panel displays, semiconductor devices or the like.
2. Related Background Art
In the plant for manufacturing flat panel displays or semiconductor devices, it is usual to group the same type of substrate processing apparatus such as CVD, PVD, and etching apparatus in a clean room to form a job shop or xe2x80x9cbayxe2x80x9d and transfer the substrates to be processed between the apparatus in each job shop (interbay transportation) or between the job shops (intrabay transportation).
Conventionally, a container or open cassette having an opening on one side or multiple sides and loaded with plurality (around 20 to 25) of substrates has been used for substrate transportation. The substrate transportation with the cassette is implemented manually, but manual substrate transportation faces a difficulty due to the recent substrate size increases in diagonal or diameter. As a result, automated guided vehicle and ceiling-track guided vehicle are used for interbay transportation and intrabay transportation, respectively.
The above-mentioned conventional substrate conveyance system performs cassette-based batch processing. Batch type transportation is effective as the number of processes is lower, but in the recent job shop type production lines where a small amount of diversified products are produced, substrates are rarely transferred to the identical substrate processing apparatus and cassette-based batch type transportation can produce substrates waiting for the subsequent step in each process. This will result in a large amount of WIP (Work in Process) from the viewpoint of overall manufacturing process. The WIP can push up the product price and also delay the time required for the whole production process.
Single substrate conveyance system has been taken into consideration so far to remove such an undesirable effect, but single-substrate type transportation performed with an automated guided vehicle or ceiling-track guided vehicle can complicate the vehicle""s traveling routes with a control difficulty and requires a clean room size increase. The clean room size increase can cause a product cost increase. In addition, as the automated guided vehicle is operated at a slow speed, it is not appropriate for single substrate processing, and the ceiling-track guided vehicle has to be integrated with other transfer apparatus that performs substrate loading/unloading to and from the substrate processing apparatus, which is technically difficult.
Accordingly, it is an object of the present invention to provide a substrate conveyance system that can efficiently perform single-substrate type interbay transportation and/or intrabay transportation in the flat panel display fabrication lines or the semiconductor device fabrication lines and that can eliminate the need of a clean room.
To achieve the above-mentioned object, the present invention is characterized by a substrate conveyance system for transporting a substrate from one or more substrate sources to either one of a plurality of substrate destinations, comprising, in combination, a first transfer module including substrate holding means for holding the substrate thereon and for changing orientation of the substrate, and a first housing surrounding the substrate holding means; and a second transfer module including a second housing which can be connected with the first housing, and transfer means for transferring the substrate to or from the substrate holding means in the first housing which is connected with the second housing, the transfer means disposed inside said second housing.
With this arrangement, it is possible to form many branched substrate transport routes by properly arranging a number of combinations of the first and second transfer modules. In addition, the first transfermodule can change the orientation or direction of substrate at the junction of substrate transfer routes, thereby enabling a free alteration of the substrate transfer direction. Further, it may be allowed that the substrate holding means has a substrate transfer function and the substrate transfer means has a substrate holding function. The arrangement of the first and second transfer module combinations is preferable when it is formed like a checkerboard.
Also, providing air purification or conditioning means for controlling the cleanliness of internal space of the first housing and/or that of the second housing can maintain a high level of cleanliness in space where substrates are transferred even in the environment with reduced cleanliness.
Preferably, the substrate holding means has a surface for mounting a substrate thereon and may be rotated about a center of the substrate mounted on the surface. This design can restrict the moment of rotations caused by a substrate load to a small value and can control a load of the rotating drive mechanism.
In case where substrate detection means for detecting substrate presence or absence is provided on each of the first and second transfer modules, it will be useful to recognize the position of the substrate being in transfer by allowing the identification of the substrate transport condition.
It will be also possible to remote control the orientation changes of the substrate holding means and the transfer system""s driving in accordance with the signal sent from the substrate detection means, which will enable the management of the whole substrate conveyance system.
These and other features and advantages of the present invention will become apparent to those skilled in the art upon a reading of the following description when taken in conjunction with the drawings.